JPS582619B2 - Ultrasonic impurity meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for measuring impurity concentration in liquid metal using ultrasonic waves.

Measuring instruments based on various measurement principles have been developed as devices for measuring impurities in liquid metals, such as plugging meters, rho meters, oxygen meters, carbon meters, hydrogen meters, etc.
Plugging meters are most commonly used for controlling the purity of liquid metals.

Conventional plugging meters are equipped with a cooling device, an orifice, a flow meter, etc. in order from the upstream side of the corrugated metal flow path, and the liquid metal is circulated at a constant flow using an electromagnetic pump, etc.
A cooling device is operated to gradually cool the liquid metal while a flow meter measures the flow rate, and the impurity concentration is determined from the temperature of the liquid metal when the flow rate suddenly decreases.

In other words, when the temperature of the liquid metal is gradually lowered, at a certain temperature, compounds of the liquid metal and impurities, such as oxides, hydrides, hydroxides, and carbonates of the liquid metal, become supersaturated and flow into the orifice. Precipitate.

The further narrowing of the orifice due to the adhesion of such precipitates is detected by detecting a sudden drop in flow rate.

Since the presence or absence of precipitates is detected by changing the flow rate, it is difficult to measure unless the liquid temperature is lowered until the amount of deposits becomes large. It takes a considerable amount of time to return to a measurable state, and sometimes the orifice becomes completely blocked due to excessive precipitation.

Furthermore, it also has the disadvantage of being expensive because it requires a flow meter and an electromagnetic pump.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ultrasonic impurity meter that can eliminate the drawbacks of the prior art as described above, shorten measurement time, and prevent complete occlusion of the orifice.

That is, the present invention provides a cooling device on the upstream side of the liquid metal flow path.
An orifice section is provided on the downstream side, an ultrasonic oscillating section and an ultrasonic receiving section are arranged in the orifice section so as to face each other, a temperature detector is provided near the orifice section, and the temperature is gradually controlled by the cooling device. This is an ultrasonic impurity meter that measures the impurity concentration from the change in the received ultrasonic wave height and the liquid metal temperature at that time.

The present invention will be explained in more detail below based on the accompanying drawings.

The drawing is a schematic explanatory diagram of an impurity meter according to the present invention.

A bypass flow is taken out by an inflow pipe 1 connected to the main loop through which the liquid metal flows, and is led back to the economizer 2 through an economizer 2, a cooling/heating device 3, and an orifice section 4, and the liquid metal flows into the main loop through an outflow pipe 5. For outflow, the devices are interconnected by piping to form a bypass system.

The orifice section 4 is a slightly elongated narrow flow path provided in the middle of the piping, and an ultrasonic oscillating section and a vibration receiving section are provided so as to face the orifice section 4 .

That is, a pair of guide rods 5a and 5b are inserted at opposing positions so as to penetrate the wall of the orifice portion 4, and are fixed by welding. An ultrasonic oscillator 8 is connected to the rod 7a, and an acoustic-electrical transducer 7b is fixed to the outer end of the other guide rod 6b.

The output of the acoustic-electrical transducer 7b is sent to the signal processing device 10 via the amplifier 9, where it stores the wave height A of the ultrasonic wave when no impurities are deposited in the orifice portion 4, and
Measure the ratio B/A of the ultrasonic wave height B during cooling,
The result is sent to the recording device 11, and the comparison result as to whether the ratio value B/A is below a certain set value is sent to the control device 1.
2.

The control device 12 controls the cooling and heating operation of the cooling and heating device 3.

Further, a thermocouple 13 is inserted into the orifice portion 4,
The output of the thermocouple 13 is sent to a measuring device 14 and further to the recording device 11 to record a temperature signal together with the ultrasonic signal.

The operation of the ultrasonic impurity meter of this embodiment will be explained as follows.

A part of the liquid metal flowing in the main loop is guided to the bypass system and circulated.

If the temperature of the liquid metal is sufficiently high, no impurities will be deposited in the orifice portion 4.

The oscillator 8 oscillates an electric signal with a constant amplitude of 2 to 3 MHz, and continues to supply it to the electro-acoustic transducer 7a.

Then, it is converted into ultrasonic vibration by the transducer 7a,
Guide rod 5a, liquid metal at orifice part, guide rod 6b
is propagated, received by the acoustic-electrical transducer 7b, and converted into an electrical signal.

The output of the acoustic-electrical transducer 7b is sent to the signal processing device 10 via the amplifier 9, and the wave height A of the ultrasonic reception signal when no impurities are precipitated is stored.

Next, the cooling/heating device 3 is operated by the control device 12 to gradually lower the temperature of the liquid metal flowing through the device, and the temperature of the liquid metal near the orifice portion 4 is detected by the thermocouple 13 and measured. The measuring device 14 and the recording device 11 continue to measure and record continuously.

The output of the acoustic-electrical transducer 7b is also continuously sent to the signal processing device 10, and the ratio B/A between the wave height B of the received signal and the wave height A of the received signal at the high temperature is determined and recorded. The device 11 continues recording.

When the temperature of the liquid metal drops below a certain temperature, supersaturated impurities begin to precipitate on the inner wall surface of the orifice portion 4, and as a result, the wave height B of the ultrasonic reception signal obtained from the acoustic-electrical transducer 7b decreases.

If a change in B/A (below l) is detected, this is the plug starting point, and the temperature measured at that time is the plugging temperature.

The signal processing device 10 is equipped with a comparator, and compares the B/A value obtained as described above with a preset value (for example, 0.9), and determines the B/A value as set. When the temperature drops below this value, a signal is sent to the control device 12 to switch the operation of the cooling/heating device 3 from cooling to heating.

Then, the temperature of the liquid metal flowing through the orifice section 4 gradually rises, and the precipitates eventually dissolve in the liquid metal, so the value of B/A approaches 1, and the orifice section 4 returns to its original state. .

When B/A becomes approximately 1, the signal processing device 10 sends a signal to the control device 12 to switch the operation of the cooling/heating device 3 from heating to cooling again.

By repeating such operations, the concentration of impurities in the liquid metal can be measured.

Although the embodiments of the present invention have been described in detail above, it goes without saying that the present invention is not limited to the apparatus of this embodiment.

Signal processing after receiving the ultrasonic waves propagating through the orifice, temperature detection, temperature control of liquid metal, configuration of the ultrasonic oscillating section and the receiving section, etc. are subject to various design changes using conventionally known methods and devices. Of course it is possible.

Since the present invention is an ultrasonic impurity meter configured as described above, it eliminates the need for electromagnetic pumps, electromagnetic flowmeters, etc. that were conventionally required, and is not only inexpensive, but also shortens measurement time. This has excellent effects such as being able to prevent complete occlusion.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings are explanatory diagrams of one embodiment of the present invention. 3... Cooling and heating device, 4... Orifice section, 5a, 5b... Guide rod, 7a...
...Electric-acoustic transducer, 7b... Acoustic-electrical transducer, 8... Oscillator, 10... Signal processing device, 11... Recording device , 13...
thermocouple.

Claims (1)

[Claims] 1. A cooling device is provided on the upstream side of the liquid metal flow path, an orifice section is provided on the downstream side, an ultrasonic oscillating section and an ultrasonic receiving section are arranged in the orifice section so as to face each other, and a temperature control device is provided near the orifice section. The ultrasonic device is characterized in that it is equipped with a detector and measures the impurity concentration from the change in received ultrasonic wave height as the temperature is gradually lowered by the cooling device and the liquid metal temperature at that time. Sonic impurity meter.